Market design is more complicated than mechanism design. And so is achieving good social outcomes.

Marketplaces are often small parts of large markets, and so potential marketplace participants may have large strategy sets, that include actions taken outside of the marketplace. And markets require social support, so the behavior of people who do not intend to participate in the market may nevertheless be important for market design. This talk will illustrate these points with some examples, drawing on experience from the design of school choice systems and kidney exchange clearinghouses.